NHD Paediatric Hub

Nutrition for exams: achieving full potential

Aliya heads up our Paediatric Hub this month. Here she examines the understanding of teenage nutrition and highlights how the environment impacts the food choices of these young people.

Twitter: @aliyaporter
Facebook: @porter_nutrition

Aliya Porter, RNutr

Freelance Registered Nutritionist

At this time of year, many young people are preparing for, or are in the middle of, exams. Achieving their full potential is important. When you look online, there are a lot of articles about eating well for exams with tips such as eating regular meals, keeping hydrated, limiting caffeine and alcohol intake, avoiding energy drinks and eating your five a day. But is there any evidence that this information helps exam performance beyond it being good practice for general health?

There are numerous studies looking at overall diet and the link to exam results. The balance of the evidence suggests that breakfast consumption is positively associated with exam results,(1) and fast-food consumption is negatively associated.(2) There are likely to be a number of confounding factors in these links and some of the studies reported weak evidence. Four more recent studies are listed here:

  1. 1677 Lebanese university students were questioned about their eating habits and exam scores. The results showed that having breakfast  ≥4 days per week compared to less than 2 days was significantly associated with higher Subjective Academic Achievement Scale (SAAS) scores. A higher number of days of eating out was significantly associated with lower SAAS scores. Neither the composition of the foods consumed for breakfast, nor the foods eaten out were considered.(3)
  2. A study of 608 medical students at Damascus University (4) revealed consistent negative associations between specific dietary habits (daily consumptions) and self-reported average grades, including tea (B = -0.334, p = 0.022), instant coffee (B = -0.682, p = 0.001), and weekly fast-food consumption (B = -0.583, p = 0.038). These are weak associations but negative associations all the same and although they were adjusted for age, gender and residency, they did not look at the whole diet, making it impossible to say whether these foods in themselves were an issue or whether dietary patterns were more significant.
  3. 577 students in the USA self-reported their Grade Point Average (GPA) along with their current habits. GPA did not change along with weekly rates of milk, vegetables, green salad, fruit (both juice and fresh fruit) consumption, however breakfast consumption had a positive effect on self-reported GPA, whilst fast food consumption had a negative effect.(5)
  4. In a systematic review and meta-analysis of iron supplementation studies in school age children, iron supplementation improved intelligence, attention and concentration, and memory but did not affect school achievement. The studies that gave the supplement for less than four months showed limited effect.(6)

The importance of micronutrients

Taken as a whole, the balance of the literature suggests that breakfast and limiting fast-food consumption in the general diet is helpful in terms of cognition and grades.

Aside from breakfast and limiting fast food, what else can our young people do to maximise their potential? Again, the research base focuses more on long-term diet rather than diets the night before.

The evidence points to the importance of micronutrients.

Iron and vitamin B12 have been linked to cognitive function. Indeed, one of the symptoms of both iron deficiency is 'tiredness and lack of energy' (7) (making it hard to concentrate) and B12 deficiency anaemia is 'problems with memory, understanding and judgment (cognitive changes)' (8) Iron is a specific issue amongst girls, according to the NDNS data. There was evidence of both iron-deficiency anaemia (as indicated by low haemoglobin levels) and low iron stores (plasma ferritin) in 9% of older girls and 5% of adult women, an issue which has been getting worse since 2008.(9) Although the systematic review above suggested general supplementation did not affect school achievement, addressing iron deficiency anaemia is important for overall health and may improve attainment.

Unlike in the research into diet more broadly, there are more studies focused on school-age children when it comes to micronutrients. Two such studies are listed here:

  1. A study of 317 Korean children revealed vitamin C (also seen in adults) and potassium intake showed a positive correlation with symbol digit modalities (SDMT) results (p <0.05). Vitamin B1 intake showed a positive correlation with the results of digit span forward tasks and SDMT (p <0.01). Vitamin B6 intake showed a positive correlation with the results of digit span forward tasks (p <0.01). 
  2. A further study of 399 primary school-age children in Ghana showed mean previous day’s intake for folate (p<0.001), vitamin B6 (p = 0.018), iron (p<0.001), and zinc (p = 0.001) differed significantly between the cognitive test score percentiles of the children.(10)

So, there is a good evidence base for a long-term healthy balanced diet when it comes to concentration, cognition and good, although less extensive evidence, related to attainment. However, there is a lack of evidence when it comes to the short-term impact of nutrition during the exam period.

Does that mean that messaging for students around exam time needs to change?

The lack of evidence on short-term diet impact does not imply it is not important, it just means more research is needed. Giving nutrition information around exam time may not benefit in the short-term when it comes to grades, but it is an opportunity when students are potentially more receptive to thinking about the link between diet and cognition as they strive for excellence. Positive changes could have a longer-term impact on their diet and, therefore, still be worthwhile. Perhaps, if anything, the nutrition information needs to be given earlier to have more chance of impacting grades and the messaging could include the need for these habits to be sustained rather than cramming good nutrition like you might do for exams.

With the cost-of-living crisis and the rise in food insecurity the fact that some school children and students may not just be eating the wrong diet for maximising cognition but may also not be consuming sufficient calories for their energy needs. Messaging for students needs to be sensitive to these issues and provide children, students and families the necessary support.

Looking at the specific common recommendations: As nutrition professionals it is widely accepted that energy drinks, alcohol and caffeine are not the best hydration, often providing a dip in energy a while after consumption. There is also extensive evidence, examined in my article in NHD in May 2020,(11) that good hydration supports mental well-being and concentration. It is also widely accepted that fruit and vegetables, regular meals and a balanced diet with sufficient micronutrients are essential for a good microbiome, mental and physical health.


More evidence is needed around the short-term impact of improving nutrition around exam time. Having a healthy balanced diet which includes breakfast, reduces fast food consumption and meets micronutrient needs can have an impact on attainment. Sharing this information in a practical, non-judgemental way is a vital part of exam preparation and student welfare.


  1. Burrows, T. L. et al (2017). Associations between Dietary Intake and Academic Achievement in College Students: A Systematic Review. Healthcare (Basel, Switzerland)5(4), 60. https://doi.org/10.3390/healthcare5040060. Accessed 15th March 2024 from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5746694
  2. Alqahtani, Y. et al (2020) Relationship between nutritional habits and school performance among primary school students in Asser Region. Journal of Family Medicine and Primary Care 9(4):p 1986-1990, April 2020. | DOI: 10.4103/jfmpc.jfmpc_885_19 Accessed 15th March 2024 from https://journals.lww.com/jfmpc/fulltext/2020/09040/relationship_between_nutritional_habits_and_school.37
  3. Hammoudi Halat D et al (2023) Exploring the effects of health behaviors and mental health on students' academic achievement: a cross-sectional study on Lebanese university students BMC Public Health. 2023 Jun 26;23(1):1228. doi: 10.1186/s12889-023-16184-8. Accessed 15th March 2024 - https://pubmed.ncbi.nlm.nih.gov/37365573/
  4. Bitar, A. et al )2024) Dietary and smoking habits during the exam period and their effect on the academic achievement among Syrian medical students. BMC Med Educ. 2024 Jan 12;24(1):60. doi: 10.1186/s12909-023-04950-6. Accessed https://pubmed.ncbi.nlm.nih.gov/38216913/ on 15th March 2024
  5. Reuter, P. R et al (2021) The influence of eating habits on the academic performance of university studentsJ Am Coll Health. 2021 Nov-Dec;69(8):921-927. doi: 10.1080/07448481.2020.1715986. Epub 2020 Feb 6. https://pubmed.ncbi.nlm.nih.gov/32027236/
  6. Gutema, B. T. et al (2023). Effects of iron supplementation on cognitive development in school-age children: Systematic review and meta-analysis. PloS one18(6), e0287703. https://doi.org/10.1371/journal.pone.0287703 Accessed 15th March 2024 from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10298800/
  7. NHS (2024) Iron deficiency anaemia Accessed on 15th March 2024 at https://www.nhs.uk/conditions/iron-deficiency-anaemia/
  8. NHS (2023) Symptoms-Vitamin B12 or folate deficiency anaemia. Accessed on 15th March 2024 from https://www.nhs.uk/conditions/vitamin-b12-or-folate-deficiency-anaemia/symptoms/
  9. Public Health England (2020) Official Statistics: NDNS: results from years 9 to 11 (combined) – statistical summary. Published 11 December 2020. Accessed 15th March 2024 from: https://www.gov.uk/government/statistics/ndns-results-from-years-9-to-11-2016-to-2017-and-2018-to-2019/ndns-results-from-years-9-to-11-combined-statistical-summary
  10. Mantey AA (2021) Iron status predicts cognitive test performance of primary school children from Kumasi, Ghana PLOS ONE 16(5): e0251335. https://doi.org/10.1371/journal.pone.0251335 Accessed on 15th March 2024 at https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0251335
  11. Porter, A. (2020) Hydration: Quenching our Thirst. Network Health Digest. May 2020 issue. Found at: https://library.myebook.com/NHD/network-health-digest-march-20-issue-152/2286/#page/17